11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/mm/mincore.c 31da177e4SLinus Torvalds * 42f77d107SLinus Torvalds * Copyright (C) 1994-2006 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * The mincore() system call. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds #include <linux/pagemap.h> 115a0e3ad6STejun Heo #include <linux/gfp.h> 121da177e4SLinus Torvalds #include <linux/mm.h> 131da177e4SLinus Torvalds #include <linux/mman.h> 141da177e4SLinus Torvalds #include <linux/syscalls.h> 1542da9cbdSNick Piggin #include <linux/swap.h> 1642da9cbdSNick Piggin #include <linux/swapops.h> 174f16fc10SNaoya Horiguchi #include <linux/hugetlb.h> 181da177e4SLinus Torvalds 197c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 201da177e4SLinus Torvalds #include <asm/pgtable.h> 211da177e4SLinus Torvalds 221e25a271SNaoya Horiguchi static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr, 231e25a271SNaoya Horiguchi unsigned long end, struct mm_walk *walk) 24f4884010SJohannes Weiner { 25f4884010SJohannes Weiner #ifdef CONFIG_HUGETLB_PAGE 26f4884010SJohannes Weiner unsigned char present; 271e25a271SNaoya Horiguchi unsigned char *vec = walk->private; 281e25a271SNaoya Horiguchi 29f4884010SJohannes Weiner /* 301e25a271SNaoya Horiguchi * Hugepages under user process are always in RAM and never 311e25a271SNaoya Horiguchi * swapped out, but theoretically it needs to be checked. 32f4884010SJohannes Weiner */ 331e25a271SNaoya Horiguchi present = pte && !huge_pte_none(huge_ptep_get(pte)); 341e25a271SNaoya Horiguchi for (; addr != end; vec++, addr += PAGE_SIZE) 3525ef0e50SJohannes Weiner *vec = present; 361e25a271SNaoya Horiguchi walk->private = vec; 37f4884010SJohannes Weiner #else 38f4884010SJohannes Weiner BUG(); 39f4884010SJohannes Weiner #endif 401e25a271SNaoya Horiguchi return 0; 41f4884010SJohannes Weiner } 42f4884010SJohannes Weiner 431da177e4SLinus Torvalds /* 441da177e4SLinus Torvalds * Later we can get more picky about what "in core" means precisely. 451da177e4SLinus Torvalds * For now, simply check to see if the page is in the page cache, 461da177e4SLinus Torvalds * and is up to date; i.e. that no page-in operation would be required 471da177e4SLinus Torvalds * at this time if an application were to map and access this page. 481da177e4SLinus Torvalds */ 4942da9cbdSNick Piggin static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff) 501da177e4SLinus Torvalds { 511da177e4SLinus Torvalds unsigned char present = 0; 521da177e4SLinus Torvalds struct page *page; 531da177e4SLinus Torvalds 5442da9cbdSNick Piggin /* 5542da9cbdSNick Piggin * When tmpfs swaps out a page from a file, any process mapping that 5642da9cbdSNick Piggin * file will not get a swp_entry_t in its pte, but rather it is like 5742da9cbdSNick Piggin * any other file mapping (ie. marked !present and faulted in with 583c18ddd1SNick Piggin * tmpfs's .fault). So swapped out tmpfs mappings are tested here. 5942da9cbdSNick Piggin */ 6031475dd6SHugh Dickins #ifdef CONFIG_SWAP 610cd6144aSJohannes Weiner if (shmem_mapping(mapping)) { 620cd6144aSJohannes Weiner page = find_get_entry(mapping, pgoff); 630cd6144aSJohannes Weiner /* 640cd6144aSJohannes Weiner * shmem/tmpfs may return swap: account for swapcache 650cd6144aSJohannes Weiner * page too. 660cd6144aSJohannes Weiner */ 6731475dd6SHugh Dickins if (radix_tree_exceptional_entry(page)) { 680cd6144aSJohannes Weiner swp_entry_t swp = radix_to_swp_entry(page); 69f6ab1f7fSHuang Ying page = find_get_page(swap_address_space(swp), 70f6ab1f7fSHuang Ying swp_offset(swp)); 7131475dd6SHugh Dickins } 720cd6144aSJohannes Weiner } else 730cd6144aSJohannes Weiner page = find_get_page(mapping, pgoff); 740cd6144aSJohannes Weiner #else 750cd6144aSJohannes Weiner page = find_get_page(mapping, pgoff); 7631475dd6SHugh Dickins #endif 771da177e4SLinus Torvalds if (page) { 781da177e4SLinus Torvalds present = PageUptodate(page); 7909cbfeafSKirill A. Shutemov put_page(page); 801da177e4SLinus Torvalds } 811da177e4SLinus Torvalds 821da177e4SLinus Torvalds return present; 831da177e4SLinus Torvalds } 841da177e4SLinus Torvalds 851e25a271SNaoya Horiguchi static int __mincore_unmapped_range(unsigned long addr, unsigned long end, 861e25a271SNaoya Horiguchi struct vm_area_struct *vma, unsigned char *vec) 871da177e4SLinus Torvalds { 8825ef0e50SJohannes Weiner unsigned long nr = (end - addr) >> PAGE_SHIFT; 8942da9cbdSNick Piggin int i; 90f4884010SJohannes Weiner 91f4884010SJohannes Weiner if (vma->vm_file) { 9242da9cbdSNick Piggin pgoff_t pgoff; 931da177e4SLinus Torvalds 94f4884010SJohannes Weiner pgoff = linear_page_index(vma, addr); 95f4884010SJohannes Weiner for (i = 0; i < nr; i++, pgoff++) 96f4884010SJohannes Weiner vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff); 97f4884010SJohannes Weiner } else { 98f4884010SJohannes Weiner for (i = 0; i < nr; i++) 99f4884010SJohannes Weiner vec[i] = 0; 1004f16fc10SNaoya Horiguchi } 1011e25a271SNaoya Horiguchi return nr; 1024f16fc10SNaoya Horiguchi } 1034f16fc10SNaoya Horiguchi 1041e25a271SNaoya Horiguchi static int mincore_unmapped_range(unsigned long addr, unsigned long end, 1051e25a271SNaoya Horiguchi struct mm_walk *walk) 106f4884010SJohannes Weiner { 1071e25a271SNaoya Horiguchi walk->private += __mincore_unmapped_range(addr, end, 1081e25a271SNaoya Horiguchi walk->vma, walk->private); 1091e25a271SNaoya Horiguchi return 0; 1101e25a271SNaoya Horiguchi } 1111da177e4SLinus Torvalds 1121e25a271SNaoya Horiguchi static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, 1131e25a271SNaoya Horiguchi struct mm_walk *walk) 1141e25a271SNaoya Horiguchi { 1151e25a271SNaoya Horiguchi spinlock_t *ptl; 1161e25a271SNaoya Horiguchi struct vm_area_struct *vma = walk->vma; 1171e25a271SNaoya Horiguchi pte_t *ptep; 1181e25a271SNaoya Horiguchi unsigned char *vec = walk->private; 1191e25a271SNaoya Horiguchi int nr = (end - addr) >> PAGE_SHIFT; 1201e25a271SNaoya Horiguchi 121b6ec57f4SKirill A. Shutemov ptl = pmd_trans_huge_lock(pmd, vma); 122b6ec57f4SKirill A. Shutemov if (ptl) { 1231e25a271SNaoya Horiguchi memset(vec, 1, nr); 1241e25a271SNaoya Horiguchi spin_unlock(ptl); 1251e25a271SNaoya Horiguchi goto out; 1261e25a271SNaoya Horiguchi } 1271e25a271SNaoya Horiguchi 1281e25a271SNaoya Horiguchi if (pmd_trans_unstable(pmd)) { 1291e25a271SNaoya Horiguchi __mincore_unmapped_range(addr, end, vma, vec); 1301e25a271SNaoya Horiguchi goto out; 1311e25a271SNaoya Horiguchi } 1321e25a271SNaoya Horiguchi 1331e25a271SNaoya Horiguchi ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); 1341e25a271SNaoya Horiguchi for (; addr != end; ptep++, addr += PAGE_SIZE) { 13542da9cbdSNick Piggin pte_t pte = *ptep; 13642da9cbdSNick Piggin 137f4884010SJohannes Weiner if (pte_none(pte)) 1381e25a271SNaoya Horiguchi __mincore_unmapped_range(addr, addr + PAGE_SIZE, 1391e25a271SNaoya Horiguchi vma, vec); 140f4884010SJohannes Weiner else if (pte_present(pte)) 14125ef0e50SJohannes Weiner *vec = 1; 1420661a336SKirill A. Shutemov else { /* pte is a swap entry */ 14342da9cbdSNick Piggin swp_entry_t entry = pte_to_swp_entry(pte); 1446a60f1b3SJohannes Weiner 145c313dc5dSWeijie Yang if (non_swap_entry(entry)) { 146c313dc5dSWeijie Yang /* 147c313dc5dSWeijie Yang * migration or hwpoison entries are always 148c313dc5dSWeijie Yang * uptodate 149c313dc5dSWeijie Yang */ 15025ef0e50SJohannes Weiner *vec = 1; 15142da9cbdSNick Piggin } else { 15230fcffedSNick Piggin #ifdef CONFIG_SWAP 15333806f06SShaohua Li *vec = mincore_page(swap_address_space(entry), 154f6ab1f7fSHuang Ying swp_offset(entry)); 15530fcffedSNick Piggin #else 15630fcffedSNick Piggin WARN_ON(1); 15725ef0e50SJohannes Weiner *vec = 1; 15830fcffedSNick Piggin #endif 15942da9cbdSNick Piggin } 16042da9cbdSNick Piggin } 16125ef0e50SJohannes Weiner vec++; 1621e25a271SNaoya Horiguchi } 16342da9cbdSNick Piggin pte_unmap_unlock(ptep - 1, ptl); 1641e25a271SNaoya Horiguchi out: 1651e25a271SNaoya Horiguchi walk->private += nr; 1661e25a271SNaoya Horiguchi cond_resched(); 1671e25a271SNaoya Horiguchi return 0; 168e48293fdSJohannes Weiner } 169e48293fdSJohannes Weiner 170f4884010SJohannes Weiner /* 171f4884010SJohannes Weiner * Do a chunk of "sys_mincore()". We've already checked 172f4884010SJohannes Weiner * all the arguments, we hold the mmap semaphore: we should 173f4884010SJohannes Weiner * just return the amount of info we're asked for. 174f4884010SJohannes Weiner */ 175f4884010SJohannes Weiner static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec) 176f4884010SJohannes Weiner { 177f4884010SJohannes Weiner struct vm_area_struct *vma; 17825ef0e50SJohannes Weiner unsigned long end; 1791e25a271SNaoya Horiguchi int err; 1801e25a271SNaoya Horiguchi struct mm_walk mincore_walk = { 1811e25a271SNaoya Horiguchi .pmd_entry = mincore_pte_range, 1821e25a271SNaoya Horiguchi .pte_hole = mincore_unmapped_range, 1831e25a271SNaoya Horiguchi .hugetlb_entry = mincore_hugetlb, 1841e25a271SNaoya Horiguchi .private = vec, 1851e25a271SNaoya Horiguchi }; 186f4884010SJohannes Weiner 187f4884010SJohannes Weiner vma = find_vma(current->mm, addr); 188f4884010SJohannes Weiner if (!vma || addr < vma->vm_start) 189f4884010SJohannes Weiner return -ENOMEM; 1901e25a271SNaoya Horiguchi mincore_walk.mm = vma->vm_mm; 19125ef0e50SJohannes Weiner end = min(vma->vm_end, addr + (pages << PAGE_SHIFT)); 1921e25a271SNaoya Horiguchi err = walk_page_range(addr, end, &mincore_walk); 1931e25a271SNaoya Horiguchi if (err < 0) 1941e25a271SNaoya Horiguchi return err; 19525ef0e50SJohannes Weiner return (end - addr) >> PAGE_SHIFT; 1961da177e4SLinus Torvalds } 1971da177e4SLinus Torvalds 1981da177e4SLinus Torvalds /* 1991da177e4SLinus Torvalds * The mincore(2) system call. 2001da177e4SLinus Torvalds * 2011da177e4SLinus Torvalds * mincore() returns the memory residency status of the pages in the 2021da177e4SLinus Torvalds * current process's address space specified by [addr, addr + len). 2031da177e4SLinus Torvalds * The status is returned in a vector of bytes. The least significant 2041da177e4SLinus Torvalds * bit of each byte is 1 if the referenced page is in memory, otherwise 2051da177e4SLinus Torvalds * it is zero. 2061da177e4SLinus Torvalds * 2071da177e4SLinus Torvalds * Because the status of a page can change after mincore() checks it 2081da177e4SLinus Torvalds * but before it returns to the application, the returned vector may 2091da177e4SLinus Torvalds * contain stale information. Only locked pages are guaranteed to 2101da177e4SLinus Torvalds * remain in memory. 2111da177e4SLinus Torvalds * 2121da177e4SLinus Torvalds * return values: 2131da177e4SLinus Torvalds * zero - success 2141da177e4SLinus Torvalds * -EFAULT - vec points to an illegal address 215ea1754a0SKirill A. Shutemov * -EINVAL - addr is not a multiple of PAGE_SIZE 2161da177e4SLinus Torvalds * -ENOMEM - Addresses in the range [addr, addr + len] are 2171da177e4SLinus Torvalds * invalid for the address space of this process, or 2181da177e4SLinus Torvalds * specify one or more pages which are not currently 2191da177e4SLinus Torvalds * mapped 2201da177e4SLinus Torvalds * -EAGAIN - A kernel resource was temporarily unavailable. 2211da177e4SLinus Torvalds */ 2223480b257SHeiko Carstens SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len, 2233480b257SHeiko Carstens unsigned char __user *, vec) 2241da177e4SLinus Torvalds { 2252f77d107SLinus Torvalds long retval; 2262f77d107SLinus Torvalds unsigned long pages; 2272f77d107SLinus Torvalds unsigned char *tmp; 2281da177e4SLinus Torvalds 2292f77d107SLinus Torvalds /* Check the start address: needs to be page-aligned.. */ 23009cbfeafSKirill A. Shutemov if (start & ~PAGE_MASK) 2311da177e4SLinus Torvalds return -EINVAL; 2322f77d107SLinus Torvalds 2332f77d107SLinus Torvalds /* ..and we need to be passed a valid user-space range */ 2342f77d107SLinus Torvalds if (!access_ok(VERIFY_READ, (void __user *) start, len)) 2351da177e4SLinus Torvalds return -ENOMEM; 2362f77d107SLinus Torvalds 237ea1754a0SKirill A. Shutemov /* This also avoids any overflows on PAGE_ALIGN */ 2382f77d107SLinus Torvalds pages = len >> PAGE_SHIFT; 239e7bbdd07SAlexander Kuleshov pages += (offset_in_page(len)) != 0; 2402f77d107SLinus Torvalds 2412f77d107SLinus Torvalds if (!access_ok(VERIFY_WRITE, vec, pages)) 2422f77d107SLinus Torvalds return -EFAULT; 2432f77d107SLinus Torvalds 2442f77d107SLinus Torvalds tmp = (void *) __get_free_page(GFP_USER); 2452f77d107SLinus Torvalds if (!tmp) 2464fb23e43SLinus Torvalds return -EAGAIN; 2472f77d107SLinus Torvalds 2482f77d107SLinus Torvalds retval = 0; 2492f77d107SLinus Torvalds while (pages) { 2502f77d107SLinus Torvalds /* 2512f77d107SLinus Torvalds * Do at most PAGE_SIZE entries per iteration, due to 2522f77d107SLinus Torvalds * the temporary buffer size. 2532f77d107SLinus Torvalds */ 2542f77d107SLinus Torvalds down_read(¤t->mm->mmap_sem); 2556a60f1b3SJohannes Weiner retval = do_mincore(start, min(pages, PAGE_SIZE), tmp); 2562f77d107SLinus Torvalds up_read(¤t->mm->mmap_sem); 2572f77d107SLinus Torvalds 2582f77d107SLinus Torvalds if (retval <= 0) 2592f77d107SLinus Torvalds break; 2602f77d107SLinus Torvalds if (copy_to_user(vec, tmp, retval)) { 2612f77d107SLinus Torvalds retval = -EFAULT; 2622f77d107SLinus Torvalds break; 2632f77d107SLinus Torvalds } 2642f77d107SLinus Torvalds pages -= retval; 2652f77d107SLinus Torvalds vec += retval; 2662f77d107SLinus Torvalds start += retval << PAGE_SHIFT; 2672f77d107SLinus Torvalds retval = 0; 2682f77d107SLinus Torvalds } 2692f77d107SLinus Torvalds free_page((unsigned long) tmp); 2702f77d107SLinus Torvalds return retval; 2711da177e4SLinus Torvalds } 272